The term “cosmetic” is used to cover any substance as defined in EEC Directive 76/768 as amended by Directive 93/35 of Jun. 14, 1993.
The article “Integrating the digitized back-scattered image to measure absorption of reduced-scattering coefficients in vivo” by Gobin et al., published in the journal Applied Optics, of Jul. 1, 1999, describes measurements of diffusion and absorption coefficients performed in the laboratory on bare skin.